The members of the Committee appointed to examine the dissertation o

Bilge Altunakar

Today's consumers prefer foods with convenience, variety, adequate shelf-life, reasonable cost and environmental soundness, promoting the interest in nonthermal food processing technologies. Pulsed electric fields (PEF) technology exhibits potential especially for fruit juice preservation by providing safety while retaining nutritional and sensory quality. Moreover, combination of PEF with antimicrobials appears to be even more promising. This dissertation explores the possibility of increasing PEF efficiency by using this technology in combination with selected antimicrobials to preserve apple cider. Chapter 1 introduces an extensive literature review on the fundamental aspects of PEF technology from a historical and technical point of view. Chapter 2 reviews the food preservation applications of PEF with emphasis on low and high acid liquid food products. Chapter 3 presents the effect of PEF in combination with sodium benzoate, potassium sorbate, cinnamic acid and hydrogen peroxide on microbial inactivation of E. coli (ATCC 11775). Selected antimicrobials at two concentrations (500 and 1000 ppm) are combined with PEF for selected electric field intensities (25-40 kV/cm) and number of pulses (5, 12, 20). The extent of synergistic microbial inactivation achieved by each combination is compared to the PEF alone treatment. Chapter 4 explores the applicability of four mathematical models (Bigelow, H lsheger, Peleg and Weibull) to predict the microbial response of E.coli (ATCC 11775) in apple cider treated by PEF and selected antimicrobials. The advantages and limitations of each model based on the accuracy factors are evaluated. Chapter 5 investigates some of the engineering aspects contributing to PEF system efficiency. The effects of electrical components, energy density and fluid flow rate on the microbial inactivation are studied. Chapter 6 evaluates the combined effect of PEF and selected antimicrobials on shelf-life of apple cider. Microbiological and chemical changes such as yeast and total bacteria growth, color, pH, titratable acidity and polyphenoloxidase (PPO) activity in apple cider during refrigerated and room temperature storage are monitored. Chapter 7 concludes the overall results for the use of PEF in combination with selected antimicrobials as a promising alternative to thermal pasteurization for fruit juices with extended shelf-life and improved quality. Specific areas of interest that require further research are mentioned and recommended as future work

Altunakar, Bi̇lge

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Food preservation by pulsed electric fields and selected antimicrobials

https://rex.libraries.wsu.edu/view/delivery/01ALLIANCE_WSU/12404571300001842/13404641520001842

FOOD PRESERVATION BY PULSED ELECTRIC FIELDS AND SELECTED ANTIMICROBIALS By

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